I have to agree with the above couple of posts. So far you list what is wrong with all these single women and that's why things don't work out. Poor you, you keep running into these wrong women! Well if you DO meet a woman who could be 'right' you may be scaring them off.
It's daunting the dating scene. The idea that you will develop a relationship with someone, fall in love that you will both feel the same way. You are asking for someone to fall for BOTH of you. The way you speak I'd not even consider dating either of you because it's already unbalanced. It's you two, and then a third woman. Now you might even SAY, "But we will want you to be an equal part of this relationship!" but how can they believe that when it's not that you are two people looking for someone you both could get to know and care about and could maybe care about both of you and equally. Even without going out on one date, it's set up that there's an imbalance. A you two, and a them. Who wants to 'join' a relationship? Especially when if anything goes wrong it's going to be their fault!? You have already made it clear it's this individual woman and not either of you. Not that one or both of you haven't gotten to know them well, or one of you likes them more than the other or has connected to her more than the other. It's always the woman. Not an ideal situation. Neither a novelty or exotic.
Me: Late 30s pansexual poly.
DH: My husband of 19 yrs and father of 3 teen girls.
DC: LDR of +4 year